In the past, various devices have been proposed for cleaning and maintaining bar screens in suitable operating condition. It is important that screens remain clean to ensure the waterway does not become obstructed due to material accumulating on the bar screen. If such accumulation does occur, the waste waterway may back-up and cause flooding of the upstream area. In order to minimize this occurance, a number of automatic cleaning devices have been proposed that are timed to clean the bar screen on a regular basis. In a number of these devices, such as that disclosed in Canadian application Ser. No. 213,050; a rake member is inserted through the bar screen and projects beyond the bars, such that when it is drawn upward, any accumulated material on the bar members is removed. However, if large objects have accumulated at the base of the bar screen the rake is prevented from being fully inserted through the bar screen. This prevents the rake from cleaning the full height of the bar screen and the large objects remain at the base of the screen. Furthermore, depending on the exact design of the cleaning apparatus damage to the rake may occur when large objects are encountered.
The present invention is designed to overcome a number of the problems of the prior art systems by providing a modified bar screen that minimizes the problems caused by large objects.